Relay



L. J. sMxTH Feb 10, 1942. l

RELAY Filed .July 2o, 193% mY Y l @y l QN 20W/"ence JAY/773273 hot water heating systems.

Patented Feb. 10, 1942 UNITED STATES PATENT OFFICE i RELAY Lawrence J. Smith, Oak Park, Ill.

Application July 20, 1938, Serial No. 220,163

2 claims. (ci. 23e-68) My invention relates to relays and moreiparticularly to a device for-controlling a line voltage circuit by an electrically connected, low voltage circuit.

Whilenot restricted thereto, my improved relay possesses special value in connection with In such installations, the temperature of the boiler water is ordinarily maintained by a firing means under the control of a boiler aquastatand circulation of this hot water through the system is effected by a pump whose operation is controlled by a room, thermostat. The pumpis ordinarily motor driven at line voltage, but a considerably lower voltage can be and usually is applied to the room proved relay shown connected to a typical circuit, the switch elements of the relay being open.

thermostat, approximately twenty-iive volts or less, with a considerable saving in installation cost, since it is unnecessary to connect the thermostat to the remainder of the circuit by armoredcable or through steel conduit. In alternating current circuits, the required voltage reduction is accomplishedv by employing a transformer and connecting this unit with the ordinary relay.l If direct current is used, either a number of batteries must be relied upon to energize the holding coil of the circuit when the room thermostat' closes, or line voltage must be applied to the thermostat directly or reduced by passage through a resistance.

It is therefore one object of my invention to devise a relay which may be employed with either alternating or direct current and which, in addition to its ordinary relay function of determining the operation of the controlled circuit by a condition occurring in the controlling circuit, also acts to reduce the voltage applied to the last-noted circuit.

A further object is to provide a relay of the character indicated in which the closing of the -controlled circuit is elected by the combined action of heat emitted by a voltage reducing eleinent provided in the controlling circuit and a thermally actuated element located in the controlled circuit.

A. further objectis to provide a relay in which the voltage reducing and thermalA actuated functions are combined in a single element. f

These and further objects of :my invention will beset forth in the following speciiication, reference being had to the accompanying drawing, and the novel-means by which said objects are effectuated will be definitely pointed out in the claims.

In the drawing:

Figure l is a sectional elevation of my im- Fig. 2 is a fragmentaryelevation o the relay showing the switch elements closed.

- Fig. 3 is an elevation of a modied type of relay, with parts broken away, andshowing the voltage reducing and thermal actuated functions of the relay combined in a single element. Referring to Figs. 1 and 2 of the drawing, the numeral I0 designates the casing of a cartridge type relay which is shown by way of illustration only, the casing in the present instance being of glass, although it may be composed of other materials. ,The .casing is completely enclosed and the atmosphere within the casing is preferably exhausted, or the interiorthereoi Vmay be illled withany of the inert gases customarily employed in mercury tube' switches or electricI light bulbs in order to prevent oxidation of the switch contacts of the device. It is contemplated, however, that all of the operating elements of my relayl may be exposed to the air without affecting the elementary inventive conception involved.

A wire II including a resistance I2 is disposed Within the casing I0 and the ends of this wireare sealed through the end walls of the casing for electrical connection to terminals I3 and I4. The terminal I3 is connected by a wire I5 to a source of electrical energy having the usual line voltage, say about volts, while the terminal I4 is connected by a wire I6 to a room thermostat Il which may be positioned to receive heat from the usual room radiator. The thermostat is also connected by a wire I8 to a terminal I9 having electrical connection with one end of a wire 20 that is sealed through the adjacent wall of the casing III then extends across the interior of the casing and is sealed through the opposite end wall for electrical connection to a terminal 22 that in turn is connected by a wire 23.130 a wire 24, thus completing the electrical circuit between the room thermostat and the source of electrical power. In the type of relay shown, the wire 2li includes a resistance 2l, comparable to the resistance I2, and, where two of such resistances Vare employed, they may occupy the spaced relation shown for a purpose presently explained. It is contemplated, however, that only one resistance may be used', since its purpose is to reduce lthe line voltage to a point enabling the use of ordinary wiring for the wires I5 and i8, and also to emitsuicient heat to operate the thermal actuatedI element hereinafter described. In a typical alternating circuit installation, the line voltage may be approximately 110 volts, and the resistances i2 and Il may then be adjusted to provide for a voltage reduction down to volts or less for application to the room thermostat.

A terminal 25 is mounted on .the casing l0 between the terminals Il and i9 and is connected by a wire 28 to a motor 21 which operates the circulating pump in the heating system, and which generically represents any electrically operated device that the relay is intended to control in the same way that the room thermon stat I1 broadly represents the controlling ele mentor the arrangement, The motor 21 is conn nected by u Wire 2B to the power wire 24.

The terminal 25 is electrically connected to one end of a conductor that is sealed through the adjacent end wall of the casing and withzln this casing has mounted thereon and in elecn trical connection therewith the intermediate porm tion of a bimetallic strip element 3i) which muy have the generally circular shape as indicated in Fig. l, or any other desired configuration. The element may be composed of any oi the customary metals ordinarily employed for purpose, but with the metallic strip having the highest coeiilcicnt of thermal expansion located interiorly of the element so to provide tor the movement of the element presently ein plained. As already noted, the intermediate por-n tion of the element 3U is fired to the conductor 29, but the ends of the element are forked to embrace one end of a conductor 3i with the element ends overlapping each other and posi tloned between abutment collars 32 and 32' pro vided on the conductor 3|. Accordingly, when the element is heated by the resistances l2 and 2I and cooled, the conductor 3l will be shifted endwise toward the right and left, respectively, as viewed in Fig. l.

The opposite end of the conductor 3iA is provided with a switch contact 33 and adjacent thereto, an insulating collar 34 is secured on the conductor. A cross arm 35 is fixed on the collar 3l and extends in opposite directions from the axis of the conductor 3| to have pivotally connected to each end thereof one end of a link 36 Whose opposite ends, respectively, are pivotally connected to the ends of a band spring 31 whose intermediate portion is ixedly connected to a collar 3B that 4is mounted on. a conductor 39 within the casing IU. A coil spring 4U encircles the conductor 39, one end thereof abutting against the collar 38 and the opposite end being connected to a; sleeve Il that is slldable on the conductor 39 and carries a switch contact l2 positioned in operative relation to the contact 33. The other end of the conductor 39 is sealed through the adjacent end wall of the casing and l is electrically connected to a terminal 43 which may be connected by a wire M tothe terminal I3 or direct to the power line 2l.

In describing the operation of my improved relay, it will be assumed that the switch contacts 33 and 42 occupy the open position shown in Fig. 1, corresponding to an open circuit position of the room thermostat i1. When the thermostat I1 closes in response to a demand for heat, for example, the electrical circuit through the resstances I2 and ZI is completed, so that these portions of the relay reduce the voltage at the thermostat and begin to emit heat which is received by the bimetallic element 30. The material selected for the resistances I2 and 2I may be such that the resistances become incandescent when current passes therethrough. By this arrangement, more heat is generated and the relay is characterized by quicker action. Tungsten or any of the materials customarily used as filaments in electric light bulbs may be employed for this purpose. Accordingly, the conductor 3| begins to shift toward the right and, because of the toggle-like relation between the links 3B, cross arm 35 and band spring .31, the ends of the spring are forced outwardly against the spring tension until the conductor 3l has moved sumciently to permit the ends of the spring to again approach each other with a sudden movement, and thus eilect a snap engagement oi the contacts tit and it. iin electrical circuit is then completed from the power source through the motor 21 and this circuit remains ln operation until the room thermostat il is satisfied, and at that time, the 'thermostat opens and thc circuit through the resistances it and ill which thereupon begin to cool rapidly. The loi-metallic element 3u begins to contract and moves the conductor 3l toward. the lett to resume the position shown in Fig. l. luring the early phase oi the latter action, engagement oi the switch elements 33 and 42 maintained by the spring di] which, when the contacts are iirst engaged, yields slightly' to provide a cushion for the endwise movement of the conductor tl; When the cooling has proceeded to a certain extent, the switch contacts 33 and ft2 will be separated rap idly by the band 31 due to the toggle connection' thus reducing the possibility of excessive arcing between the contacts which would otherwise pit and corrode these portions of the relay.

The modification shown in Fig. 3 diiers essentally from that illustrated in l'iig. l by combining in one element the functions carried out by the resistance l2 or 2i and bimetallic element 3D. As before, the numeral 45 designates the casing of the relay 'which is provided at one end with terminals 4B, 41 and IIB, corresponding, respectively, to terminals I4, 25 and il? in. Fig. i, and at the opposite end with terminals 49, 5U and 5I, corresponding respectively to terminals I3, 43 and 22. The corresponding terminals in Fig. .'-l may he linked in a circuit arrangement as shown in lig. l.

The terminal t6 is electrically connected to a bimetallic strip element 52 that located within the casing t5 and preferably arranged as a spiral, While the terminal all is similarly connected to a like element 53, the two elements being gcncrally spaced from each other as indicated in Fig. 3 and embodying sufficient resistance to provide for the required voltage reduction. The opposite ends of the elements 52 and 53 are connected to a cross arm 54 composed of suitable insulation whose intermediate portion is fast upon a conductor 55 having a switch contact 59 which, in the relation of parts shown in Fig. 3, is spaced from a contact 6I) that is electrically connected to a conductor 6I which extends outwardly of the casing for connection to the terminal 5U. The material having the greatest coemcent of thermal expansion is located interiorly of each spiral thereby insuring an unwinding thereof when heated. Further, the spirals are wound in opposite directions so as to obtain the desired pushing action on the arm 54. The inner end of each spiral is fixed, while the outer and free end may be slotted to receive a headed pin 62 on the arm 5I and thus substantially avoid any turning effort on the arm. The combination of band spring and toggle arrangement for efby the numeral 63 and this portion of the construction is similar to that illustrated in Fig. 1. The conductor 55 is connected by a wire 56 t0 the terminal 41, while the ends of the bimetallic elements 52 and 53 adjacent the ends of the cross arm 54 are connected by wires 51 and 58, respectively, t0 the terminals 49 and 5I, respectively. Y The operation of the relay illustrated in .'ig 3 is generally similar to that already discussed, except that when current is traversing the elements 52 and 53, their tendency to unwind .shifts the cross arm 54 toward the right to thereby close the contacts 59 land 60. Snap disengagement o the contacts is eiected in the manner already described for the relay shown in Fig. l.

claim:

l. An electrical system for regulating the circulation of water through a lhot Water heating system in response to demands for heat comprising a thermostat positioned to be affected by a radiator forming a part of the heating system, the thermostat being closed only when de-` manding heat for the radiator and open at all other times. a motor for operating a pumpto control water circulation, a source of electrical power, and a relay electrically connected to the thermostat and source, the connection including a resistance for effecting a voltage drop whereby the voltage applied to the thermostat is low in comparison with the source voltage, electrical connections between the motor and the source and including a thermo-actuated element positioned to receive heat from the resistance, and switch means actuated to closure bythe heated element.

2. An electrical system for regulating the supply of heat to a radiating means comprising a member responsive to temperature changes and positioned in operable relation to the radiating means, the temperature' responsive means being closed only when demanding heat for the radiating means and open at all other times, and a relay having a resistance electrically connected to the temperature responsive means for eiecting a voltage drop whereby the voltage applied to the temperature responsive member is low in comparison with the source voltage, a thermo-actuated element positioned to receive the heat from the resistance, and switch means actuated to closure by the heat element for controlling the passage of heat to the radiating-means.

LAWRENCE J. SMITH. 

